Comparative screening of recombinant antigen thermostability for improved leptospirosis vaccine design

Recombinant antigens exhibit targeted protectiveproperties and offer important opportunities in the development of therapeutic technologies. Biophysical and structural methods have become important tools for the rational design and engineering of improved antigen-based vaccines. Vaccines containing Leptospira immunoglobulin-like (Lig) protein-derived antigens are currently the most promising candidates for protective immunity against the globally prevalent bacterial pathogen, Leptospira interrogans; however, vaccine trials using these domains have produced inconsistent results. Here, we compare the thermostability of domains from the main immunogenic regions from major leptospiral antigens, LigA and LigB. By measuring temperature-dependent fluorescence decay of the hydrophobic core tryptophan, 17 individual Lig protein immunoglobulin-like (Ig-like) domains were shown to display a broad range of unfolding temperatures. For a majority of the domains, stability issues begin to occur at physiologically relevant temperatures. A set of chimeric Ig-like domains was used to establish the ability of transplanted domain regions to enhance thermostability. Further insights into the determinants for domain stabilization were explored with nuclear magnetic resonance dynamics and mutational analysis. The current study has yielded a set of thermostable Ig-like domain scaffolds for use in engineering antigen-based vaccines and demonstrates the importance of incorporating thermostability screening as a design parameter.     

Normothermic liver ischemia and antioxidant treatment during hepatic resections.

The purpose of our study was to evaluate the clinical impact of reperfusion injury after normothermic ischemia during major liver resections and the effect of an intraoperative antioxidant infusion. This prospective randomized study comprised 50 patients; half of them (treatment group) were given an antioxidant infusion containing tocopherol and ascorbate immediately prior to reperfusion onset. Venous blood samples for the determination of MDA-TBARS (malondialdehyde-thiobarbituric acid reactive substances) by a HPLC-based test as a marker of lipid peroxidation were taken prior to ischemia, 30 min after reperfusion onset and at the end of the operation. In the control group there was a significant increase of MDA-TBARS (p = 0.001) at 30 min after reperfusion onset. At the end of the operation the values had returned to the initial level. The treatment group showed only a marginal increase (p-value for the difference between the two groups: 0.007). After exclusion of the patients with histologically proven advanced cirrhosis the increase in the control group (p < 0.001) and the difference between the increase in the two groups (p = 0.001) became more significant. Prothrombin time was also significantly better in the treatment group (p = 0.003). Postoperative complications such as prolonged liver failure, bleeding disorders and infections were seen more often in the control group. In our study MDA-TBARS was increased after liver ischemia, but in patients with advanced cirrhosis the effect was smaller or even absent. This increase and possible clinical consequences of reperfusion injury could be reduced by intraoperative administration of an antioxidant infusion.     

Heat stress in a high-latitude seabird: effects of temperature and food supply on bathing and nest attendance of great skuas Catharacta skua

Birds such as great skuas Catharacta skua adapted for successful breeding at high latitudes may experience problems of heat dissipation in mild climates. Great skuas spend time bathing at freshwater sites close to breeding territories and here, we examine impacts of heat stress on bathing, foraging and nest attendance of adults during three breeding seasons with marked variation in the availability of prey (1-group sandeels Ammodytes marinus ). Adults exhibited diurnal variation in bathing activity that matched heat-stress conditions. Moreover more birds bathed on days of higher average heat stress, suggesting that bathing plays a role in thermoregulation. Bathing numbers were lower in years of poor food availability, when adult attendance at territories was low, probably because lower attendance reduced the opportunity for parents to bathe without leaving chicks unattended. Chicks are normally guarded by female parents and fed by males but under conditions of low food availability territorial attendance of breeding pairs was particularly low on days of high heat stress, with chicks regularly left unattended at air temperatures exceeding 14°C. Unattended chicks are at risk of being killed by neighbouring conspecifics and survival of chicks to fledging was low in the two years of low sandeel stocks. Our study indicates that for great skuas, indirect effects of climate change on prey stocks and direct effects on heat stress experienced by adults may be additive.     

Effects of pineal factors on the action potentials of sympathetic neurons

Neurons from rat superior cervical ganglia were grown in coculture with pineal cells. Action potentials of neurons in cocultures were 25% longer and were 25% greater in amplitude than those recorded from neurons grown in the presence of ganglionic nonneuronal cells alone. Neurons showed an increase in action potential duration with increasing time in culture. This may have been related to the recovery of nonneuronal cell populations after an initial exposure to the antimitotic agent Ara-C. In cultures not initially exposed to Ara-C, a subsequent exposure after 7 days in culture resulted in a shortening of the action-potential duration. Neuronal cultures were exposed to gel slabs containing the pineal indolamines, serotonin, N-acetylserotonin, and melatonin. Serotonin and N-acetylserotonin showed no effect on the neuronal action potentials at the concentrations tested. Melatonin caused an increase in action-potential duration that was associated not with an increase in action-potential amplitude, but with a decrease in action-potential rise rates. The effects of long-term exposure in melatonin appeared to be reversible in some cells but not in all. Short-term effects of melatonin were observed in older cultures and in younger cultures after the cells were stimulated repeatedly. Older cultures also had higher levels of spontaneous activity. The dependence of the short-term effects of melatonin on electrical activity may suggest a role for melatonin as a neuromodulator.     

Spirochaeten im Rhizopodenplasma

Zusammenfassung Im Plasma der SüßwasserforaminifereBiomyxa vagans wird das Vorkommen von aktiv beweglichen Spirochaeten beschrieben.